Std logic 1164.vhd
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-- COPYRIGHT 1993-1996 BY THE INSTITUTE OF ELECTRICAL AND ELECTRONICS
-- ENGINEERS, INC.
-- 345 EAST 47TH STREET
-- NEW YOPRK, NY 10017, USA
-- ALL RIGHTS RESERVED
-- --------------------------------------------------------------------
-- --------------------------------------------------------------------
--
-- Title : std_logic_1164 multi-value logic system
-- Library : This package shall be compiled into a library
-- : symbolically named IEEE.
-- :
-- Developers: IEEE model standards group (par 1164)
-- Purpose : This packages defines a standard for designers
-- : to use in describing the interconnection data types
-- : used in vhdl modeling.
-- :
-- Limitation: The logic system defined in this package may
-- : be insufficient for modeling switched transistors,
-- : since such a requirement is out of the scope of this
-- : effort. Furthermore, mathematics, primitives,
-- : timing standards, etc. are considered orthogonal
-- : issues as it relates to this package and are therefore
-- : beyond the scope of this effort.
-- :
-- Note : No declarations or definitions shall be included in,
-- : or excluded from this package. The "package declaration"
-- : defines the types, subtypes and declarations of
-- : std_logic_1164. The std_logic_1164 package body shall be
-- : considered the formal definition of the semantics of
-- : this package. Tool developers may choose to implement
-- : the package body in the most efficient manner available
-- : to them.
-- :
-- --------------------------------------------------------------------
-- modification history :
-- --------------------------------------------------------------------
-- version | mod. date:|
-- v4.200 | 01/02/92 |
-- --------------------------------------------------------------------
library std ;
use std.standard.all ;
PACKAGE std_logic_1164 IS
-------------------------------------------------------------------
-- logic state system (unresolved)
-------------------------------------------------------------------
TYPE std_ulogic IS ( 'U', -- Uninitialized
'X', -- Forcing Unknown
'0', -- Forcing 0
'1', -- Forcing 1
'Z', -- High Impedance
'W', -- Weak Unknown
'L', -- Weak 0
'H', -- Weak 1
'-' -- Don't care
);
-------------------------------------------------------------------
-- Directives for synthesis of std_ulogic.
-- Declare the type encoding attribute and set the value for std_ulogic
-- Directives for the resolution function and all other function are
-- in the package body
-------------------------------------------------------------------
ATTRIBUTE logic_type_encoding : string ;
ATTRIBUTE logic_type_encoding of std_ulogic:type is
-- ('U','X','0','1','Z','W','L','H','-')
('X','X','0','1','Z','X','0','1','X') ;
-------------------------------------------------------------------
-- unconstrained array of std_ulogic for use with the resolution function
-------------------------------------------------------------------
TYPE std_ulogic_vector IS ARRAY ( NATURAL RANGE <> ) OF std_ulogic;
-------------------------------------------------------------------
-- resolution function
-------------------------------------------------------------------
FUNCTION resolved ( s : std_ulogic_vector ) RETURN std_ulogic;
-------------------------------------------------------------------
-- *** industry standard logic type ***
-------------------------------------------------------------------
SUBTYPE std_logic IS resolved std_ulogic;
-------------------------------------------------------------------
-- unconstrained array of std_logic for use in declaring signal arrays
-------------------------------------------------------------------
TYPE std_logic_vector IS ARRAY ( NATURAL RANGE <>) OF std_logic;
-------------------------------------------------------------------
-- common subtypes
-------------------------------------------------------------------
SUBTYPE X01 IS resolved std_ulogic RANGE 'X' TO '1'; -- ('X','0','1')
SUBTYPE X01Z IS resolved std_ulogic RANGE 'X' TO 'Z'; -- ('X','0','1','Z')
SUBTYPE UX01 IS resolved std_ulogic RANGE 'U' TO '1'; -- ('U','X','0','1')
SUBTYPE UX01Z IS resolved std_ulogic RANGE 'U' TO 'Z'; -- ('U','X','0','1','Z')
-------------------------------------------------------------------
-- overloaded logical operators
-------------------------------------------------------------------
FUNCTION "and" ( l : std_ulogic; r : std_ulogic ) RETURN UX01;
FUNCTION "nand" ( l : std_ulogic; r : std_ulogic ) RETURN UX01;
FUNCTION "or" ( l : std_ulogic; r : std_ulogic ) RETURN UX01;
FUNCTION "nor" ( l : std_ulogic; r : std_ulogic ) RETURN UX01;
FUNCTION "xor" ( l : std_ulogic; r : std_ulogic ) RETURN UX01;
FUNCTION "xnor" ( l : std_ulogic; r : std_ulogic ) RETURN UX01;
FUNCTION "not" ( l : std_ulogic ) RETURN UX01;
-------------------------------------------------------------------
-- vectorized overloaded logical operators
-------------------------------------------------------------------
FUNCTION "and" ( l, r : std_logic_vector ) RETURN std_logic_vector;
FUNCTION "and" ( l, r : std_ulogic_vector ) RETURN std_ulogic_vector;
FUNCTION "nand" ( l, r : std_logic_vector ) RETURN std_logic_vector;
FUNCTION "nand" ( l, r : std_ulogic_vector ) RETURN std_ulogic_vector;
FUNCTION "or" ( l, r : std_logic_vector ) RETURN std_logic_vector;
FUNCTION "or" ( l, r : std_ulogic_vector ) RETURN std_ulogic_vector;
FUNCTION "nor" ( l, r : std_logic_vector ) RETURN std_logic_vector;
FUNCTION "nor" ( l, r : std_ulogic_vector ) RETURN std_ulogic_vector;
FUNCTION "xor" ( l, r : std_logic_vector ) RETURN std_logic_vector;
FUNCTION "xor" ( l, r : std_ulogic_vector ) RETURN std_ulogic_vector;
-- -----------------------------------------------------------------------
-- Note : The declaration and implementation of the "xnor" function is
-- specifically commented until at which time the VHDL language has been
-- officially adopted as containing such a function. At such a point,
-- the following comments may be removed along with this notice without
-- further "official" ballotting of this std_logic_1164 package. It is
-- the intent of this effort to provide such a function once it becomes
-- available in the VHDL standard.
-- -----------------------------------------------------------------------
FUNCTION "xnor" ( l, r : std_logic_vector ) RETURN std_logic_vector;
FUNCTION "xnor" ( l, r : std_ulogic_vector ) RETURN std_ulogic_vector;
FUNCTION "not" ( l : std_logic_vector ) RETURN std_logic_vector;
FUNCTION "not" ( l : std_ulogic_vector ) RETURN std_ulogic_vector;
-------------------------------------------------------------------
-- conversion functions
-------------------------------------------------------------------
FUNCTION To_bit ( s : std_ulogic; xmap : BIT := '0') RETURN BIT;
FUNCTION To_bitvector ( s : std_logic_vector ; xmap : BIT := '0') RETURN BIT_VECTOR;
FUNCTION To_bitvector ( s : std_ulogic_vector; xmap : BIT := '0') RETURN BIT_VECTOR;
FUNCTION To_StdULogic ( b : BIT ) RETURN std_ulogic;
FUNCTION To_StdLogicVector ( b : BIT_VECTOR ) RETURN std_logic_vector;
FUNCTION To_StdLogicVector ( s : std_ulogic_vector ) RETURN std_logic_vector;
FUNCTION To_StdULogicVector ( b : BIT_VECTOR ) RETURN std_ulogic_vector;
FUNCTION To_StdULogicVector ( s : std_logic_vector ) RETURN std_ulogic_vector;
-------------------------------------------------------------------
-- strength strippers and type convertors
-------------------------------------------------------------------
FUNCTION To_X01 ( s : std_logic_vector ) RETURN std_logic_vector;
FUNCTION To_X01 ( s : std_ulogic_vector ) RETURN std_ulogic_vector;
FUNCTION To_X01 ( s : std_ulogic ) RETURN X01;
FUNCTION To_X01 ( b : BIT_VECTOR ) RETURN std_logic_vector;
FUNCTION To_X01 ( b : BIT_VECTOR ) RETURN std_ulogic_vector;
FUNCTION To_X01 ( b : BIT ) RETURN X01;
FUNCTION To_X01Z ( s : std_logic_vector ) RETURN std_logic_vector;
FUNCTION To_X01Z ( s : std_ulogic_vector ) RETURN std_ulogic_vector;
FUNCTION To_X01Z ( s : std_ulogic ) RETURN X01Z;
FUNCTION To_X01Z ( b : BIT_VECTOR ) RETURN std_logic_vector;
FUNCTION To_X01Z ( b : BIT_VECTOR ) RETURN std_ulogic_vector;
FUNCTION To_X01Z ( b : BIT ) RETURN X01Z;
FUNCTION To_UX01 ( s : std_logic_vector ) RETURN std_logic_vector;
FUNCTION To_UX01 ( s : std_ulogic_vector ) RETURN std_ulogic_vector;
FUNCTION To_UX01 ( s : std_ulogic ) RETURN UX01;
FUNCTION To_UX01 ( b : BIT_VECTOR ) RETURN std_logic_vector;
FUNCTION To_UX01 ( b : BIT_VECTOR ) RETURN std_ulogic_vector;
FUNCTION To_UX01 ( b : BIT ) RETURN UX01;
-------------------------------------------------------------------
-- edge detection
-------------------------------------------------------------------
FUNCTION rising_edge (SIGNAL s : std_ulogic) RETURN BOOLEAN;
FUNCTION falling_edge (SIGNAL s : std_ulogic) RETURN BOOLEAN;
-------------------------------------------------------------------
-- object contains an unknown
-------------------------------------------------------------------
FUNCTION Is_X ( s : std_ulogic_vector ) RETURN BOOLEAN;
FUNCTION Is_X ( s : std_logic_vector ) RETURN BOOLEAN;
FUNCTION Is_X ( s : std_ulogic ) RETURN BOOLEAN;
END std_logic_1164;